Portable refrigerator



FIG. 1 is a perspective view of a portable refrigerator showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is a perspective view thereof shown in an alternate position. 

The ornamental design for a portable refrigerator, as shown and described. 